It is well known in the air valve art to provide valves which can be employed in stacks, and wherein the inlet air pressure to each valve is individually controlled. However, the prior art system for sandwiching pressure controls between units in a stack, for each valve in a stack of valves is expensive and bulky. A prior art system for providing individual pressure control means for each valve in a stack of valves includes the mounting of a plate between the valve body and the valve base, which increases the height of the valve substantially because of the large structural configurations of the conventional type pressure regulators employed in such plates, which are normally called sandwich plates. The drastic increase in the height of a valve caused by the use of a sandwich plate is a disadvantage where space for the valve is at a minimum, since it results in an overall larger valve. The use of a sandwich plate is also disadvantageous when a predetermined dimensional control must be maintained between a valve body and a valve base, or where certain connections are made between a valve body and a valve base, such as electrical connections. Flow control valves have been used before in exhaust ports in more complicated structures, as in U.S. Pat. Nos. 2,912,007 and 2,992,511.